Regulation and Enhancement of Angiogenesis in Dense Fibrin Matrices

描述（由申请人提供）：血管生成，即从现有脉管系统中萌发新的毛细血管，是一种复杂的生物学过程，对于治疗多种病理和组织工程的成功至关重要。在组织工程中促进血管生成的许多有前途的策略中包括具有精确空间和时间控制的促血管生成分子的受控递送。另一种方法是递送适当的细胞类型，其可以提供促进血管生成的信号的更生理性的混合物，这将加速宿主血管的募集。PI与两名高级合作研究者一起，开始在毛细血管形态发生的稳健、基于纤维蛋白的3-D体外模型中探索后一种策略。使用该模型系统，其支持形成具有明确管腔的稳定（> 3周）毛细血管样结构，我们已经表明毛细血管形态发生被增加的纤维蛋白基质密度显著抑制。此外，我们已经表明，这种纤维蛋白密度阻滞部分是由于内皮细胞无法上调局部重塑基质和维持毛细血管浸润所需的基质金属蛋白酶（MMP）的一个子集。然而，骨髓来源的间充质干细胞（MSC）的3-D组织结构的添加显着增强毛细血管形态发生，部分克服了由基质密度增加引起的抑制通过上调表达和/或活性的MMP的这一子集。基于这些初步发现，这项新的研究人员生物工程研究资助计划旨在测试MSC可以在体外和体内刺激致密的3-D纤维蛋白基质内血管生成的假设。这些目标将通过以下三个具体目标来实现：1。量化包埋在致密纤维蛋白基质中的MSC在体外增强毛细血管样网络形成的能力。2.）的情况。探讨基质金属蛋白酶（MMPs）的一个亚类（MMPs-2、MMPs-9和膜型MT 1-MMP）在MSCs促血管生成中的作用。3.）第三章确定MSC在SCID小鼠模型中在皮下部位体内刺激血管形成的能力。这些研究的成功完成将有助于我们对ECM和MMPs在血管生成中的作用的基本理解，并最终影响合成ECM类似物的设计和干细胞在组织工程应用中的使用。

DESCRIPTION (provided by applicant): Angiogenesis, the sprouting of new capillary blood vessels from existing vasculature, is a complex biological process of critical importance to the treatment of numerous pathologies and the success of tissue engineering. Amongst the many promising strategies to promote angiogenesis in tissue engineering includes the controlled delivery of pro-angiogenic molecules with precise spatial and temporal control. An alternative approach is to deliver an appropriate cell type that can provide a more physiologic mixture of pro- angiogenic cues that will accelerate the recruitment of host vessels. In conjunction with two senior co- investigators, the PI has begun to explore this latter strategy in a robust, fibrin-based 3-D in vitro model of capillary morphogenesis. Using this model system, which supports the formation of stable (> 3 weeks) capillary-like structures with well-defined lumens, we have shown that capillary morphogenesis is significantly inhibited by increasing fibrin matrix density. Furthermore, we have shown that this fibrin density block is partially due to the inability of endothelial cells to upregulate a subset of matrix metalloproteinases (MMPs) required to locally remodel the matrix and sustain capillary invasion. However, the addition of bone marrow-derived mesenchymal stem cells (MSCs) to the 3-D tissue construct significantly enhances capillary morphogenesis, partially overcoming the inhibition caused by increased matrix density by upregulating the expression and/or activity of this subset of MMPs. Building on these preliminary findings, this new investigator Bioengineering Research Grant proposal seeks to test the hypothesis that MSCs can stimulate angiogenesis within dense 3-D fibrin matrices both in vitro and in vivo. These objectives will be achieved via three specific aims as follows: 1.) Quantify the ability of MSCs embedded throughout dense fibrin matrices to enhance capillary-like network formation in vitro. 2.) Probe the roles played by a subset of MMPs (MMPs-2 and -9 and the membrane-type MT1-MMP) in the angiogenic enhancement by MSCs. 3.) Determine the ability of MSCs to stimulate vascularization in vivo in a subcutaneous site in a SCID-mouse model. Successful completion of these studies will contribute to our fundamental understanding of the role of the ECM and MMPs in angiogenesis, and will ultimately impact the design of synthetic ECM analogs and the use of stem cells in tissue engineering applications.